Magnetic vane type ratiometer



April 29, 1947.

H. D. wARsllAw MAGNETIC VANE TYPE RATIOIIETER.l

Fouad nay 16, 1945 l. A rTomEY Patented Apr. 29, 1947y O 2,419,6152 Y MAGNETIC vANE TYPE RATIOMETER Howard D. Warshaw, Drexel Hill, Pa.

Application-May 16, 1945, Serial No. 594,130 ,4

(Cl. l'l1-95)y (Granted under the act of March 3, 1883, as

6Claims.

amended April 30, 1928: 370 0.*G. 757) This invention relates to new and useful improvements in remote indicating or telemetering systems, and particularlyI to' an indicating unit that is operable to indicate a particular condition.

More particularly the present invention relates .,than,electxicallrOperaigdrindietillg unit f the 2 l Still a further object of the present invention is to provide a novelindicator unit of the stated character having means operable to pull the indieating pointer off the scalewhen the indicator is ratiometer type for use with"alternating"current"' in conjunction with a remote transmitter unit that is electrically interconnected therewith to form an impedance bridgeconstructed and arranged so that any change in a condition affect-` ing the transmitter will produce a like change in the indicating element of the indicator unit.

Indicator units of the ratiometer type produced prior to the present invention are constructed and Aarranged for -use'with-direct' current-only and will not operate with alternating current because the rotor elements thereof are such that they tend to follow the changes in polarity of the alternating current field with the result that, in the case of low frequency alternating current the rotor elements continuously hunt back and forth across the indicating scale in response to changes in the polarity of the field and, in the case'of high frequencyl alternating current, the inertia of the rotor elements is too great to permit them to move at all in response to the rapid changes in polarity, and no true indication' is obtainable in either case.

There is a definite need in industry and in the war eiort for an indicator unit of the ratiometer type that may be usedwith alternating current and, with this' in mindthe principal object of the present invention is to provide an indicating ratiometer that is constructed and arranged to provide accurate and emcient operation with a1- ternating current. f

Another object of the present invention is to provide a novel and improved indicator unit of the ratiometer type thatv is operable in response to two directionally xed magnetic fields in accordance with the ratio of the magnitudes of the aldeenergized, together with novel means operable when the indicator is energized to nullify the ei-` fect of said pull-off, means.

the various features and details of the construction and operation thereof are hereinafter fully set forth and described with reference to the accompanying drawing in which:

ternating currents producing said magnetic fields.

Fig. 1 is a sectional vewaxially through indicator unit made 'in accordance with the present invention.

Fig. 2 is a sectional view taken on line 2,2, rig. 1-.

Fig. 3 is a perspectiveview showing the construction relationship of certain operative mechanisms of the indicator unit of Fig. 1, and Fig. 4 is a schematic diagram of one type of telemetering circuit in which an indicator unit of the present invention may be connected.

Referring now to the drawing, and particularly toA Fig. 1 thereof, an indicator unit made in accordance with the present invention may include a housing or casing structure comprising a base member I and a tubular wall member 2 which may be threaded on to the base member I as indicated at 3 and provided at its other end with a window 4 of transparent material such as for example, glass, plastic or the like. Suitably secured to an upstanding iiange portion -5 of the base member I at diametrically opposite points thereon are inverted L shaped support elements 6 to each of which is secured, for example, by screws or the like l, one end of a bracket member 8. The upper ends 9 of the brackets 8 have secured thereto an arcuate lframe plate I 0, and the latter in turn has secured thereto a face plate or the like II that is provided with a suitable indicating scale I2 thereon (see Fig. 4).

Extending longitudinally of the indicator unit and parallel to the axis thereof to a point substantially adjacent the bas member l, are elongated screw or bolt members I3 that have their -The coil support form I4 is provided with a circular bore or opening I5 of substantial diameter therethrough and the coil support form Il is po sitioned upon the screws or bolts I3 in predetermined spaced relation with respect to the frame plate Iii by means of spacer sleeves I3 provided on said screws or bolts I3. At the opposite side of the coil support form Il from the spacers I6 suitable spacer sleeves I'I likewise are positioned upon the screws or bolts I3 and this assembly, comprising the spacer sleeves IB coil support form It and spacer sleeves Il are secured upon the bolts or screws i3, in the described relationship with respect to the frameplate Iii, by means oi' nuts or the like i8 which are threaded on 'said screws or bolts I3 endwise of the spacer sleeves I'l as shown.

Also positioned upon the screws or bolts I3 outwardly endwise of the nuts I3 is a cup shaped housing member Is that is composed of a material having good electrical conductivity. Endwise of this cup shaped member Is is a bracket member 2c of non-magnetic material the purpose for which will appear hereinafter. The bracket member 2t and the cup shaped housing I@ are securedupon the screws or bolts i3 in the described relationship by means oi nuts or the like 2i threaded thereon. Y

ln addition to the foregoing, there is secured upon the screws or bolts i3, for exple, by nuts or the like 22 a cup shaped shield member d3 that is composed of highly permeable magnetic material. The base of the shield cup 23 preferably is suitably spaced from the bracket member 2@ by means of suitable spacers 24 positioned uponl the screws or bolts is intermediate the shield 23 and the nutsZi previously described. As shown in the drawing the shield cup 23 has a depth such that the wall portion thereof surrounds and shields the previously mentioned bracket 23. housing I9, spacer sleeves I'l and the coil support form I4 in the manner best shown in Figs. 1 and 3 of the drawing.

Extending coaxially through the circular bore or opening I in the coil support form Il is a shaft 25 that has its opposite end portions rotatably journalled in suitable Jewel bearings 2.6 and 2l provided respectively in the frame plate I0 and in the housing I-S. As shown the bearing 23 is adjustable by means of a screw 2B held in the position to which adjusted by bow spring or the like 29. Carried by the shaft 2B adjacent the frame plate I is a, pointer member that has a portion thereof extending-outwardly beyond the frame plate Ill with .its free end portion disposed in outwardly overlying relation with respect to the face plate il, the arrangement beins such that as the shaft 25 is rotated, the free end portion of the pointer member 30 will sweep across the indicating scale I2 provided exteriorly on the dial plate II.-

suitably mounted upon the coil support form Il are two sets of coils 3l and 32 arranged so that the coils of one set are disposed at a predetermined angle with respect to the coils of the other set, for example, as best shown in Fig. 2 of the drawing. The particular 'angular relation of the two sets of coils 3| and 32 is determined by the length of the indicating scale I2 or, in other words, by the extent of sweep through which the free end portion of the pointer member 3l is adapted to travel or sweep over the dial face II relative to the scale I2 thereon, and suitable stops (not shown) are provided for limiting the movement of the pointer member -30 and shaft 25 to that extent. A

Secured upon the shaft 25 for rotation therewith within the circular bore or opening Il in the coil support form Il isa vane element 33 that is composed of highLv permeable magnetic material. The-vane element 33 may be secured upon the shalt 2l by threading the same thereon in the manner shown in the drawing so that equal portions of said vane element are disposed at l respectively opposite sides of the shaft 25 in order that the vane element 33 may be perfectly balanced rotationaliy with respect to the said shaft ber 2Q at the outer side thereof a. smaller permanent magnet 35 that is positioned with respect to tbeiindicator unit in approximately the same angular relation as the zero marl; of the indica scale I2 on the dial face il. This .mfrnt magnet 35 functions in cooperation with the permanent magnet 34 to return the shalt member 25 and its associated vane 33 and pointer 3e to thezero position of the indicator unit scale en the unit is deenergized. Buitably secured or mounted upon the bracket members 8 outwardly thereoi are circuit resistors et, 3l anden, respectively, which may take the form of coils as shown in the drawing.

.As shownvand described, the coils 3l and 32 are iixed in'position at a predetermined angle with respect to each other and it will be evident that when alternating current is caused to now throv h said coils there will be produced two mague iields that are fixed in their respective directiqns. However the resultant magnetic eld of these two directionally fixed fields will have e, direction that is a function of the ratio of the magnitudes-of the alternating currents passing through the coils 3| and 32. As previously stated the coil support form I4 is of nonmagnetic material with the result that eddy current lossesE-In that member are eliminated and there is 'nd'. obstruction or diversion of the magnetic elds oi' the coils 3| and 32 that would occur wereg the form Il fabricated of magnetic material. Furthermore, by fabricating the vane element. 3359! magnetic material characterized by its high.' supstantially constant permeability, said vane is jlighly receptive to the passage of the dields of thefpoils 3l and 32 and the rapid changes in polarityg! the alternating current do not aff ect the position of the vane 33 which will align itself, and-lignee the .pointer 30, with the resultant neld vector of the two directionaly fixed magnetic fieldsproduced by the alternating currents applied to sets of angularly` related coils. I'husbygarying the ratio of the alternating currents: l through the angular related sets of coils-3 and 32 the pointer member 30 will move over the scale I2 on the dial face I I.

Referring now to Fig. 4 of the drawing, there is illustrated-a schematic diagram of one type of telemetering circuit in which an indicator unit made according to the present invention may be employed in conjunction with a suitable transmitter unit, for example, of the type described in my 'copendins applications Serial No. 587,600 led April 10, 1945, and Serial No. 594,131 illed May ductive reactance of one coil and simultaneously decrease the inductive reactance of the other coil, the arrangement being such that the magnetic fluxes produced by the coils 39 and 40 are opposed with the result that voltage variation in the coils for a given change in position of thecore 4| is quite pronounced. As shown in said Fig. 4, three conductors 42, 43 and 44 lead from the transmitter unit to the indicator unit. The conductor 42 is connected-to one end of the indicator coil 32 while the conductor 44 is connected to one end of the indicator coil 3|, and the conductor 43 is connected through a source of alternating current 45 and the resistor 31 to the opposite ends .of said indicator coils 3| and 32. Resistors 36 and 33 are connected in parallel with the indicator coils 3| and 32, respectively, as shown.

From the foregoing it will be evident that the telemetering system shown in Fig. 4 constitutes an impedance bridge. The transmitter coils 39 and 40 make up two legs of the bridge, and the indicator coilsl3| and 32 make up theother two legs, the alternating current source 45 being connected across lthe diagonals of the bridge.

The dimensions of the magnetic circuits associated with the transmitter coils 39 and 4U are so proportioned that when pressure or nuid fiow through the transmitter is such a-s to position the core 4| midway between said coils, the inductive reactance of coil 39 is equal to that of coil 40. Thus when core 4| is in the mid position the magnetic circuit for coil 39 has a reluctance which is equal to that of the magnetic circuit for tion of the rotor assembly comprising theshaft 25, vane 33 and pointer member 30, and this magnet 35 is arranged to cooperate with the magnet 34 to pull the pointer member 30 oif the scale I2 to the zero position, through rotation Aof the' shaft 25 and vane 33,v when the coils 3| and 32 oif'the` indicator unit are deenergized.

However, when the coils of the indicator are energized resulting in actuation of the vane 33 and shaft 25 to move the pointer element 30 across the scale I2, the magnet 35 will continue to react with the magnet 34 (which rotates with the shaft 25) to produce a drag upon the free rotation of said shaft sufficient to introduce a small percentage error in the indicating position of the pointer with respect to the scale I2 on the face plate I.

According to the present invention, therefore, there is wound about the permanent magnet a number of turns of wire 46 which are arranged and connected into the telemetering circuit so that when the indicator is energized there will now through the turns of wire 46 a current having a vmagnitude and direction that will cancel or neutralize the field of the permanent pull-off magnet 35. As shown in Fig; 4, the turns of wire 46 may be connected across the alternating current source and in series with a suitable recoil 40. Therefore, with the core 4| in the mid position, the bridge circuit is balanced so that the current through the coil 3| of the indicator is the same as that through `the coil 32 thereof and the pointer 30 accordingly will take up a position on the scale |2 as shown in Fig. 4. Should the core 4|` be moved from its mid position upwardly in response to an increase in pressure or fiuid flow through the transmitter, or

. downwardly in response to a decrease in pressure or fiuid flow, itis evident that the reluctance of the magnetic circuit associated with one of thetransmitter coils will be increased while the rel luctance of the magnetic circuit associated with the other transmitter coil simultaneously will bev the resultant magnetic field, and hencey the change in the pressure or rate of uid flow through the transmitter. l

'Ihe resistor 31 is adju-stable and controls the sensitivity of the indicator unit or, in other words, governs travel of the pointer 30 for a given travel of the core 4| in the transmitter unit. Resistors 36 and 38 likewise are adjustable and govern the position of the limits of travel of the pointer 30 -with respect to the limits of thescale |2 on the dial face As previously stated, there is secured upon the bracket member 2U a permanent magnet 35 that is positioned upon the bracket 20 with its axis substantially aligned or positioned to correspond with the position of the long axis of the permanent magnet 34 in approximately the zero posisistance 41 and alternating current rectifier 49. By this arrangement it'will be observed that when the indicator unit is deenergized, the turns of wire 46 about the magnet 35 likewise are deenergized and the latter functions in its intended manner to pull the pointer 30 olf the scale I2 to the zero position thereof.

From the foregoing description it Will-be observed that the present invention provides an indicator of the ratiometer type that is constructed and arranged to provide accurate and efficient operation with alternating currents, and wherein an indicating rotor assembly is movable in response to directionally fixed magnetic fields in accordance with the ratio of the magnitudes of the alternating currents producing such fixed fields. In addition, the present invention provides an indicating unit having novel electrical means associated with an indicating pointer pulloff magnet that is operable to produce a magnetic field having a magnitude and direction that will cancel or neutralize the eld of the pull-off magnet when the indicator unit i-s energized and operating.

While the indicator unit herein shown and deis not necessary to provide, in the telemetering circuit, the alternating current rectifier 49.

lWhile a particular embodiment of the present invention has been herein illustrated and described, it is not intended that the invention be limited to such disclosure, and changes and modif fications may be embodied and incorporated within the scope of the claims.

The invention described herein may be manufactured andy used by or for the Government of andere the United States of America for governmental purposes without the payment of any royalties .axially of the bore in said coil form, a vane member of magnetic material having high permeability fixed on said shaft within the bore of said coil form, said vane being operable to align itself with the directionally resultant field of the xed magnetic fields produced by electric currents passing through said coils and thereby rotate s aid shaft. a pointer member actuable by said shaft, a face plate having an indicating scale thereon disposed with respect to the pointer so that the latter is positioned with respect to said scale according to the position of the resultant iield of the two directionally fixed magnetic fields of said coils, and a member of highly permeable magnetic material secured in surrounding relation with respect to said coil form to electrically shield the same.

2. In an indicating ratiometer ofthe type de scribed, a pair of elongated supports, a coil form of non-metallic material having a circular bore therethrough secured on said supports, coils fixedly mounted on said coil form and arranged "to align itself with the resultant field of the fixed magnetic /iields produced by electric currentspassing through said coils and thereby rotate said shaft, a pointer member actuable by said shaft, a face plate having` an indicating scale thereon disposed with respect to the pointer so that the latter is positioned with respect to said scale according to the position of the resultant field of the two fixed magnetic fields of said coils, and a permanent magnet element fixedon said shaft for rotation therewith and cooperable with said housing member to damp rotational movement of said vane member and shaft.

3. In an indicating ratiometer of the type described, a pair of elongated supports, a coil form of non-metallic material having a circular bore therethrough secured on said supports, coils iixedly mounted on said coil form and arranged in predetermined angular relation with respect to one another, a housing member of good electrical conductivity secured on said supports adjacent to one end thereof, a shaft extending through the bore of the coil form and journalled for rotation coaxially of the bore in said coil form, a vane member of magnetic material 'having high permeability fixed on said shaft within the bore of said coil form, said vane being operable to align itself with the resultant field of the directionally fixed magnetic fields produced by electric currents passing through said coils and thereby rotate said shaft, a pointer member actuable by said shaft, a face plate having an indicating scale thereon 84 disposed with respect to the pointer so that the latter is positioned with respect to said scale according to the position of the resultant eld of the two directionally fixed magnetic fields of said coils, a permanent magnet element fixed on said shaft for rotation therewith and cooperable with said housing member to damp rotational movement of `said vane member and shaft, and a 'cup shaped member of highly permeable magnetic material secured on said supports at said one end thereof and extending in the direction of the other end thereof in surrounding relation with respect to said magnet, housing member and coil form to electrically shield the same.

4. In an indicating ratiometer of the type described, a pair of supports, a coil form of nonmetallic material having a circular bore therethrough secured on said supports, coils fixedlymounted on said coil form and arranged in-predetermined angular relation with respect to one another, a shaft extending through the bore of the coll form and journalled for rotation coaxially of the bore in said coil form, a vane member of magnetic material having high constant permeability iixed on said shaft within the bore of said coil form, said vane being operable to align itself with the resultant eld of the fixed magnetic fields produced by electric currents passing through said coils and thereby rotate said shaft, a pointer member actuable by said shaft, a face plate having an indicating scale thereon dis'- posed with respect to the pointer so that the latter is positioned with respect to said scale according to the position of the resultant eld of the two fixed magnetic elds of said coils, a first permanent magnet element fixed on said shaft for rotation therewith and operable to damp rotational movement of said vane member and shaft, a second permanent magnet xedly secured with respect to the zero position of the indication scale von said face plate Acooperable with the first magnet when said coils are deenergized to rotate said shaft and vane and pull the pointer oi! said scale' to said zero position thereof, and electrical means associated with said second magnet operable when said coils are energized to neutralize said second magnet.

5. In an indicating ratiometer of the type described. a pair of supports, a coil form of nonmetallic material having a circular bore therethrough secured on said supports, coils xedly mounted on said coil form and arranged in predetermined angular relation with respect to one another, a shaft extending through the bore of the coil form and journalled for rotation coaxially of the bore in said coil form, a vane member of magnetic materia1 having high permeability fixed on said shaft within the bore of said coil form, said vane being operable to align itself with the resultant field of thedrectionally fixed magnetic fields produced by electric currents passing through said coils and thereby rotate said shaft,

-a pointer member actuable by said shaft, a face plate having an indicating scale thereon disposed with respect to the pointer so that the latter is positioned with respect to said scale according to the position of the resultant field of the two directionally xed magnetic fields of said coils, a first permanent magnet element fixed on V:said shaft for rotation therewith and operable to damp rotational movement of said 'vane member and shaft, a second permanent magnet xedly secured with respect to the zerol position of the indication scale on said face plate cooper-able with the rst magnet when said coils are deenergized to rotate said shaft and vane and pun the pointer on.' sais scale to said zero position thereof, and a mem# ber of highly permeable magnetic material secured on said supports in surrounding relation with respect to said magnets and coil form, to

Yelectrically shield the same.

coil form, a shaft extending through the bore of the coil form and journalled in said bearings for rotation coaxially 'of the bore in said coil form, a vanemember of magnetic material having high permeability fixed on said shaft within the bore of said coil form, said vane being operable to align said shaft for rotation therewith and cooperable with said housing member to damp rotational movement of said vane member andv shaft, a second permanent magnet iixedly secured with respect to the zero position of the indicating scale on said face plate'cooperable with'the first magnet when said coils are deenergized to rotate said shaft and vane and pull thea pointer ofi.' said scale to said zero position thereof, electrical means associated with said second `magnet operable when said coils are energized to neutralize the magnetic field of said second magnet, said means comprising a solenoidal winding placed about said second magnet and energized 'by suitably rectified current from the alternating current supply line. and a cup shaped member of highly permeable material secured on said supports at said one end thereof and extending in the direction of the other end thereof in surrounding relation with respect to said magnets, housing member and coil form to electrically shield the same.

HOWARD D. WARSHAW.

REFERENCES CITED itself with the resultant iield of the directionally The following references are of record in the iixed magnetic fields produced by electric currents passing through said coils and thereby rotate said shaft, a pointer member actuable by said shaft, a face plate associated with said frame member having an indicating scale thereon disposed with respect to the pointer so that the latter is positioned with respectv to said scale accoils, a iirsi'.` permanent magnet element iixed on A35 1,964,228

iile of this patent:

UNrrED s'rA'rEs PATENTS Number Name Date 2,345,011 Sias (I) Mar. 28, i944 2,354,618 Sias (II) July 25, 1944 2,362,562 Kelly Nov. 4, 1944 2,354,902 Wolferz Aug. l, 1944 2,342,947 Lingel Feb. 29, 1944ll Tanner June 26, 1934 

